Patent GB-1187121-A (GB)
Title: Variable Speed Transmission.
IPC: F16H47/08
Filed: 1967-05-03
Abstract: 1,187,121. Change-speed gear and control; friction clutches; band brakes; detent brakes; hydraulic brakes. SOC. ANON. FRANCAISE DU FERODO. 3 May, 1967 [4 May, 1966], No. 20492/67. Headings F2C, F2D, F2E and F2F. In a change-speed planet gear for a motor vehicle wherein an input shaft 10 drives an output pinion 11 through an hydraulic torque converter 13 and a four-element planet gear train 14 providing three forward and reverse ratios, the gear train reaction element 19 is held against reverse rotation for low and intermediate forward ratios by a one-way clutch 36 in series with a brake 40 and is held against forward rotation during overrun in low and intermediate ratios by a brake 37 which slips at a predetermined torque. Gear arrangement.-As shown, the planet train comprises intermeshed planets 45, 47 on an output carrier 18 and meshing suns 16, 19 and a ring gear 17. For low ratio the sun 16 is connected by a friction clutch 27 to the turbine 21 of the torque converter whilst the sun 19 is held by the one-way clutch 36 and brake 40. For intermediate ratio the clutch 27 is disengaged and the ring gear 17 is driven by the torque converter through a positive clutch 32, 34 and a friction clutch 35, whilst the sun 19 remains held. On additional engagement of the clutch 27 both the sun 16 and ring gear 17 are driven by the turbine of the torque converter to provide direct drive, the sun 19 overrunning. Reverse is provided by engaging the clutch 27 to drive the sun 16 whilst the ring gear 17 is held by a positive brake 33, 34. The brakes 37, 40 are disengaged to permit the sun 19 to rotate idly. In Fig. 5 (not shown), the planet gear comprises two sun-ring planet trains. The sun (52) of the first train may be driven through the clutch (27) whilst the planet carrier (55) of the first train and the ring gear (56) of the second train may be clutched to the torque converter turbine or held by the positive clutch-brake (32, 33, 34). The ring gear (53) of the first train and planet carrier (54) of the second are fast with the output (11) whilst the sun gear (57) of the second train is held by the brakes (37, 40). Three forward and reverse ratios are provided by engaging the clutches and brakes in the same order as described above for Fig. 1. Clutches and brakes.-The friction clutch 27 is engaged by a Belleville spring 25A and is disengaged by supplying pressure liquid to a chamber 26 which contains the driven disc 27. A valve (27A), Fig. 4 (not shown), in the clutch disc 27 permits rapid filling of the chamber 26 during disengagement but slow emptying of the chamber 26 to provide gradual drive takeup. The brake 40 may comprise a pawl engaging a toothed wheel 39 or may, Figs. 5 and 6, be an hydraulically-operated friction brake. The brake 37 which slips at a predetermined torque comprises a band 74 which is engaged with the drum 37 by a calibrated spring 75. The brake 37 is disengaged by supplying pressure liquid to a chamber 78 to move left a piston 76 against the bias of the spring 75. A parking brake pawl 41 is engageable with a toothed wheel fast with the output element 18 of the planet gear. Control.-A manually-operated ratio shift lever 60 is movable in a gate 61 shaped as shown and is connected to a two-part control valve 69, 70, to the slidable element 34 of the clutchbrake unit 32, 33, 34 and to the parking brake pawl 41. In the neutral position shown pressure liquid is supplied from a line 73 through the valve 69 to the chamber 26 to disengage the clutch 27 and the valve 70 blocks the supply to the clutch 35 and brake 40 which are thus disengaged and vents the chamber 78 so that the brake 37 is applied by the spring 75. Movement of the lever 60 to the park Pk position acts through a linkage 67, 68 to apply the parking brake pawl 41. During movement of the lever 60 from the neutral position PM to the position C a lost-motion spring coupling 71, 72 permits movement of valve spool 69 without corresponding movement of the valve spool 70. This movement of the spool 69 cuts the pressure liquid supply to the clutch 27 which is thus engaged so that the brake 37 holds the turbine 21 and positive clutch element 38 against idle drag. Movement of the lever 60 along the path 62 slides the clutchbrake element 34 axially into mesh with the clutch element 32 if the lever 60 moves towards the forward ratio path 64, or into mesh with the brake element 33 if the lever moves towards the reverse ratio path 65. As the lever 60 moves along the forward ratio path the valve spools 69, 70 follow its movement and in the low ratio position AV1 the valve 70 supplies pressure liquid to engage the brake 40 whilst the clutch 27 remains engaged. In the second ratio position AV2 the valve 69 supplies pressure liquid to the chamber 26 to disengage the clutch 27 whilst the valve 70 supplies pressure liquid to the clutch 35 and brake 40 which are both engaged. In the direct-drive position AV3 the valve 69 re-engages the clutch 27 whilst the valve 70 maintains the clutch 35 and brake 40 engaged and additionally supplies pressure liquid to the chamber 78 to disengage the brake 37. For reverse, the lever 60 is moved to the position AR in which the valves engage the clutches 27, 35 and release the brakes 37, 40.